Method and apparatus for correcting drift during automated FIB processing

Abstract

A method and apparatus for correcting drift of the beam irradiation position during automated FIB (focused ion beam) processing with a reference image-setting unit, an image read-in unit for reading in images of the reference image region during the FIB processing, an arithmetic-and-control unit for finding the direction and amount of image deviation between the subsequent images, and a beam deflection system-adjusting unit for correcting the beam deflection system by correcting the image deviation based on the deviation in response to the output from the arithmetic-and-control unit. The arithmetic-and-control unit optimizes the brightness or contrast of the reference image.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method and apparatus for correcting drift during automated focused ion beam (FIB) processing.[0003]2. Description of Related Art[0004]Where a sample surface is irradiated with a focused ion beam (FIB) by an FIB system to micromachine the surface, if the beam irradiation time is prolonged, the sample stage on which the sample is placed and electronics drift with time. Consequently, it may be impossible to perform beam lithography accurately. Especially, as design rules of semiconductor devices have become more exacting, the positional accuracy required in microlithography has decreased below 100 nm. To realize such a high positional accuracy, the amount of drift of the beam irradiation position during the lithography process needs to be reduced by a factor of about 10, i.e., be less than 10 nm. Therefore, an intrinsic mark is put on the sample. Based on positional deviation of the mark,...

AI Technical Summary

Benefits of technology

The present invention provides a method and apparatus for correcting drift during automated FIB processing of a sample. This allows for precise micromachining of the sample. The method involves setting a reference image region on the sample, obtaining a first image before ion beam irradiation, obtaining a second image (used for check) after ion beam irradiation, calculating the direction and amount of image deviation, and adjusting a beam-adjusting system based on the calculated direction and amount of image deviation. This invention ensures accurate reference image reading and sample processing accuracy.

Problems solved by technology

Consequently, it may be impossible to perform beam lithography accurately.

Because there are plural beam irradiation positions at which processing is performed, it has been difficult to reproduce the stage position accurately because of the mechanical accuracy.

This makes it impossible to precisely read the image in the reference image region.

Consequently, there arises the problem that the processing accuracy deteriorates.

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